The easiest way to install Cerberus as a system app is with the "Convert to system app" feature of Link2SD: install the app, open it, long-press on Cerberus in the list of installed apps and select "Convert to system app".
I had Cerberus installed for several years. I converted it to be a system app after watching the video. Now I secretly hope to be able to record something similar if it gets stolen.
[1] https://www.cerberusapp.com/get
After that you can set it to be run only with a specific number entered in the phone dialer, so the shortcut isn't visible in the app drawer.
You have to really know about Cerberus to find it, or be knowledgeable to re-flash the device when you steal it. That's what it makes it a very good anti-theft app.
Lifetime license otherwise costs 3$ for up to 5 active devices at the same time, so it's quite cheap. I bought it 4 years ago and used in on about 5 different Android phones, you can remove older unused devices to keep the limit down.
The main difference between this and other solutions or Android Device Manager is functionality to control the device over SMS commands. Because ADM is useless when the device doesn't have internet connectivity. Even when someone takes out your SIM and inserts another, Cerberus notifies you about the new SIM and sends you the number of it, so you can control the device over the new number.